So many questions revolve around the photos. Why is there a
bedroom underground? Does anyone sleep in that
bed? Why is the plant alive? Who created the
room? And is it the same person who took the photos?

No one knows for sure, but as
noted by CityLab, there are a lot of theories. Some on German
social media say it could belong to an impoverished student
saving on rent.

Others wonder if it's a performance art piece staged by someone
in Berlin's graffiti art scene, who could easily navigate the
tunnel's maze.